Bilateral relations between the Islamic Republic of Iran and the Kingdom of Saudi Arabia have been strained over different geo-political issues such as the interpretations of Islam, aspirations for leadership of the Islamic world, oil export policy, relations with the US and the West. Although Saudi Arabia and Iran are both Muslim majority nations and follow and rule through Islamic Scripture, their relations are fraught with hostility, tension and confrontation, due to differences in faith. Saudi Arabia is a conservative "Wahhabi" Sunni Islamic kingdom with a tradition of close ties with the United States and United Kingdom. Iran is a Twelver ShiaIslamic Republic founded in a populist anti-Western revolution. Both Saudi Arabia and Iran are seen to have aspirations for leadership of Islam, and have different visions of stability and regional order. After the Islamic Revolution, relations deteriorated considerably after Iran accused Saudi Arabia of being an agent of the US in the Persian Gulf region, representing US interests rather than Islam. Saudi Arabia is concerned by Iran''s consistent desire to export its revolution across the board to expand its influence within the Persian Gulf region -- notably in post-SaddamIraq, the Levant and within further south in addition to Iran''s controversial, much debated nuclear program.

Tensions between the two countries have waxed and waned. Relations between Saudi Arabia and Iran soured particularly after the Iranian Revolution, the nuclear program, and most recently the 2011 alleged Iran assassination plot. There have also been numerous attempts to improve the relationship. After the 1991 Gulf war there was a noticeable thaw in relations. In March 2007 PresidentAhmadinejad of Iran visited Riyadh and was greeted at the airport by King Abdullah, and the two countries were referred to in the press as "brotherly nations". After March 2011, Iran''s financial and military support for Syria during the Syrian Civil War, has been a severe blow to the improvement of relations.

The difference of political ideologies and governance has also divided both countries. The Islamic Republic of Iran is based on the principle of Guardianship of the Islamic Jurists, which holds that a faqīh (Islamic jurist) should have custodianship over all Muslim followers, including their governance and regardless of nationality. Iran''s Supreme Leader is a Shia faqīh. The founder of the Iranian revolution in 1979, Ayatollah Khomeini, was ideologically opposed to monarchy, which he believed to be unIslamic. Saudi Arabia''s monarchy, on the other hand, remains consistently conservative, not revolutionary, and politically married to age-old religious leaders of the tribes who support the monarchy and the king (namely the Custodian of the Two Holy Mosques) is given absolute obedience as long as he does not violate Islamic sharia law. Saudi Arabia has, however, a Shia minority which has recently made bitter complaints of institutional discrimination against it, specifically after the 2007 change in Iraqi governance and particularly after the 2011 events that spanned the region. At some stages it has gone as far as to call for overthrowing the king and the entire system.

Both countries are major oil & gas exporters and have clashed over energy policy. Saudi Arabia, with its large oil reserves and smaller population, has a greater interest in taking a long-term view of the global oil market and incentive to moderate prices. In contrast, Iran is compelled to focus on high prices in the short term due to its low standard of living given recent sanctions after its decade old war with Saddam''s Iraq.

Saudi Arabia and Iran established diplomatic relations in 1929 following the signing of a Saudi-Iranian Friendship Treaty. However, relations were not active until the 1960s mostly due to differences in religious practices and Iran''s recognition of Israel. In 1966 the late King Faisal of Saudi Arabia visited Iran with the aim of further strengthening relationships between both neighboring countries. The Shah of IranMohammad-Reza Pahlavi reciprocated by paying an official visit to Saudi Arabia which eventually led to a peaceful resolution of the islands. The Shah supported King Faisal''s efforts regarding Islamic solidarity and actively contributed to the establishment of multinational Islamic institutions, including the Organization of the Islamic World Congress, the Muslim World League, and the Organization of the Islamic Conference.

In 1968, Saudi Arabia and Iran signed a demarcation agreement. When the United Kingdom announced to withdraw and vacate from the Persian Gulf in the late 1960s, Iran and Saudi Arabia took the primary responsibility for peace and security in the region. In the late 1960s, the Shah sent a series of letters to King Faisal, urging him to modernize Saudi Arabia, saying, "Please, my brother, modernize. Open up your country. Make the schools mixed women and men. Let women wear miniskirts. Have discos. Be modern. Otherwise I cannot guarantee you will stay on your throne." In response King Faisal wrote, "Your majesty, I appreciate your advice. May I remind you, you are not the Shah of France. You are not in the Élysée. You are in Iran. Your population is 90 percent Muslim. Please don''t forget that."

During the 1970s, Saudi Arabia''s main concerns over Iran were firstly, Iran''s modernisation of its military and its military dominance all over the region; secondly, Iran''s repossession of the islands of Big Tunb, Little Tunb and Abu Moussa in 1971 which challenged the United Arab Emirates claim over the islands. The dispute remains till today. But the relationship between Iran and Saudi Arabia was never as friendly as between the years 1968 and 1979.

The relationship between the two countries was not without its tensions in the mid-to-late 1970s. As the Shah attempted to build an Iranian security architecture in the region, the Saudis resisted these efforts. Instead, King Khalid attempted to build bilaterial security relationships with the smaller neighboring Gulf states which has lasted till today. The Saudis also argued for more modest OPEC price increases in 1976 and 1977 than Iran wanted.

Iranian Revolution

Following the theocratic Iranian Revolution conducted by Khomeini in 1979, Iran started to openly attack and criticise the character and religious legitimacy of the Saudi system. However King Khalid, the then ruler of Saudi Arabia, sent Khomeini a congratulatory message, stating that "Islamic solidarity" could be the basis for closer relations of two countries. He also argued that with the foundation of the Islamic Republic in Iran there were no obstacles that inhibited the cooperation between two countries.

In a 1987 public address Khomeini declared that “these vile and ungodly Wahhabis, are like daggers which have always pierced the heart of the "Muslims" from the back,” and announced that Mecca was in the hands of “a band of heretics.” Upon this statement diplomatic relations between the two countries ended until 1991.

Sectarian tensions

Historically, Iran–Saudi relationships have always been uncertain, something attributed to the different sects that the majority populations in both the countries follow. Saudi Arabia which is a predominantly Sunni society has always been skeptical of Shi''ite Iran''s activities in the Persian Gulf region, thus labeling Iranian ambitions to dominate the Muslim world as a form of Safawid/Safavid rule.

Leading Sunni and Shi''ite Clerics in both the countries deemed each other''s religious beliefs as incorrect for decades. An attempt was made by the Sunnis to demolish the shrine of Imam Hussein, one of the important religious leaders of Shi''ite theology and the grandson of the Prophet Muhammad whose life is considered the main difference between Sunni and Shi''ite sects, due to Wahabbi focus on the spiritual aspect of Islam rather than the tangible. Since then, tensions between both major sects of Islam, their followers and their affiliates, have increased and this tension is considered unlikely to be resolved any time soon. According to Le Figaro, on 5 June 2010, King Abdullah of Saudi Arabia told Hervé Morin, then Defense Minister of France that: "There are two countries in the world that do not deserve to exist: Iran and Israel."

1980''s Iran–Iraq War

The Shia–Sunni conflict between the two countries also played a pivotal role in the Iran–Iraq war when Saudi authorities pledged US$25 billion of aid to the Iraqi government of Saddam Hussein. The Iran–Iraq War increased Saudi concerns over stability in the region, hence their financial support to Iraq regardless of the "not-so-warm" relations between Baathist Iraq and Conservative Saudi Arabia. In doing so, Saudi Arabia recognised its worries that revolutionary Iran was a far greater threat to its survival and the stability of the region. Saudi Arabia also encouraged other Arab states of the Persian Gulf, including Kuwait, Bahrain, Qatar and the United Arab Emirates, to do the same by giving financial support to Iraq. To cover the costs of the war Saudi Arabia dramatically increased its oil production. This increase in oil production by Saudi Arabia was aimed to weaken Iran''s ability to fund its campaigns. But this measure by Saudi Arabia did not have a desired impact on Iran because it also cost the Saudi government billions in revenue as oil prices plunged from over $30 a barrel to less than $15 by the mid 1980s.

During the Iran–Iraq war, Iran flew their aircraft in Saudi airspace and also threatened Saudi Arabia and Kuwait with severe consequences if they would not stop supporting Iraq. Unlike America, Saudi Arabia, due to its very traditional Arab-Bedouin culture, did not break diplomatic relations with Iran even during the worst periods of tension following the revolution and during the Iran–Iraq war.

1987 Hajj Incident

Until 1987, no satisfactory resolution was made to decrease the tension between Iran and Saudi Arabia. The already strained relationship between the two countries further deteriorated when clashes occurred between Iranian-led demonstrators and Saudi security forces on 31 July 1987. The clash claimed the lives of around 400 pilgrims, out of which two thirds had Iranian nationality. This incident angered the Saudis and in retaliation, the Saudi administration instituted a ban on all Hajj (Pilgrimage) rituals and activities. Angry protesters in Tehran responded by ransacking the Saudi embassy and also detained and physically attacked an number of residing Saudi diplomats. As a result, one of the Saudi officials died from the injuries. In response, Saudi Arabia in 1988, cut its diplomatic relations with Iran and ensured that no Iranian could obtain a Saudi travel visa for performing the Hajj (Pilgrimage).

Responses to Satanic Verses

The relations between Saudi Arabia and Iran gradually started to improve after the end of the Iran-Iraq war in 1988. Iran had accepted ceasefire with Iraq in July 1988 and soon afterwards, Saudi Arabia started improving relations with Iran.

In October 1988, the late King Fahd halted all media campaigns against Iran and asked Saudi administration to pressure Iraq into implementing the UNSCR 598. In 1989, Iranian President Hashemi Rafsanjani stated that Iran and Saudi Arabia were holding indirect talks to improve their relations. But the issuance of fatwa by Khomeini against the Indian author Salman Rushdie again soured the relations between the two countries. Khomeini, the spiritual leader of Iran at that time, declared a death sentence for Salman Rushdie for certain anti-Islamic remarks in his book Satanic Verses published in 1988. The Saudi government, which took this religious decree against Rushdie as an act aimed at gaining Muslim sympathy across the world, came up with its own verdict of making Rushdie appear before an Islamic tribunal before he could be delivered a death sentence.

Iraqi invasion of Kuwait in August 2, 1990

When Iraq invaded Kuwait in 1990, Iran criticised and condemned the invasion. This stance from Iran, in favor of the Kuwaitis, and the anti-Iraqi coalition of the Persian Gulf states helped to improve relations between Iran and the GCC, namely Saudi Arabia. Both Iran and Saudi Arabia rejected the use of force as a solution to regional problems and opposed the invasion of Kuwait by Iraq. Iran went further, by backing UN sanctions against Iraq. Iran viewed the Iraqi occupation of Kuwait as a serious threat, considering it the first step towards its expansionist mindset. During the war, relations between Iran and Saudi Arabia thawed considerably and the official ties were restored in 1991.

This short resumption of political ties was followed by quick high level visits, notably, in April 1991, Iranian Foreign MinisterAli Akbar Velayati visited Saudi Arabia to propose an Iranian-Gulf Cooperation Council alliance with a mandate for the security of the Persian Gulf, during a meeting with the late King Fahd. He claimed theGulf Cooperation Council was to weak and hence failed to prevent the invasion of Kuwait, and stressed the need of the inclusion of Iran to strengthen such a regional agency to ensure stability.

The Hajj (Pilgrimage) issue was also resolved. In 1991, the Saudi authorities allowed 115,000 Iranian pilgrims, which was more in number compared to the 1988 quota of 45,000, that had led to Iran''s abrupt boycott. The Saudis also agreed to an Iranian request of allowing 5,000 relatives and friends of the 412 "martyrs" of the 1987 incident to attend the Hajj Pilgrimage that year. In later years, Iran adopted a careful approach and undertook measures for preventing a repeat of that incident. Iranian authorities tried to discourage large demonstrations by its pilgrims and attempted to have them held within the confines of the Iranian encampment. (Explanation: Certain Iranian Shi''ite rituals are not accepted by other sects of Islam and could endanger the lives of Iranian Pilgrims if conducted openly).

Khobar Towers Bombing

On 23 June 1996, a massive truck bomb exploded near U.S. military barracks in Dhahran, Saudi Arabia, killing nineteen U.S. servicemen and wounding hundreds. The US government held Iran responsible for the attack. The charges against Iran, however, remained unconfirmed, and therefore did not substantively affect the Iranian-Saudi relations.

1997 OIC meeting

The 1997 meeting of the Organisation of the Islamic Conference (OIC) in Iran heralded a shift in the attitude of the Arab States towards Iran. Several Arab countries confirmed their commitment to the conference. Saudi Arabia, which was previously criticized by Iran because of its control over the main Islamic holy cities of Mecca and Medina and also because of its perceived reliance on the United States for security, also participated in the meeting. In the OIC summit meeting, Saudi Arabia was represented by Crown Prince Abdullah (currently King) and its Minister of Foreign affairs Saud Al Faisal. Saudi participation proved helpful in the process of further reconciliation between Iran and Saudi Arabia. As a result, Saudi ministerial delegations visited Iran and later on, the official visit of President Mohammad Khattami to Saudi Arabia took place in February 1998.

This was the first visit by the Iranian Premier to Saudi Arabia after the 1979 Iranian Revolution. The aim was to address pressing economic issues of the time. Iran was looking for a reallocation of OPEC (Organisation of the Petroleum Exporting Countries) producing quotas to which it required strong support from Saudi Arabia. It was also reported that Iran was trying to persuade Saudi Arabia to consider exporting the Iranian Infrastructure to Central Asia. Iran also expected that the issue of the regional security alliance would be raised in which the alliance for the security of the region could be made to ensure stability on both borders of the Persian Gulf.

A Comprehensive Cooperation Agreement was signed between Saudi Arabia and Iran in May 1998, in which both countries agreed to cooperate in the field of economics, culture and sports. The relationship between Saudi Arabia and Iran was further improved when Khatami, the then President of Iran, on his tour to neighboring Arab countries, visited Saudi Arabia in May 199. President Khatami stayed for five days in Saudi Arabia in which various discussions were held between the heads of both countries. Discussions included Persian Gulf security, efforts to increase global oil prices, the situation in Iraq and the development of a common geo-strategic approach to regional issues. The partial détente between Iran and the USA encouraged Saudi Arabia to apply more cooperation with President Khatami. In addition to this, Saudi Arabia and Iran signed an agreement known as the Saudi-Iranian security agreement in April 2001.

In July 1999, the late King Fahd of Saudi Arabia urged other Persian Gulf countries to improve their relations with Iran. King Fahd of Saudi Arabia, speaking at the opening session of the Shura Council said that it was in the interest of all the countries of the Persian Gulf to improve relations with Iran. He further said that all the other countries should follow Saudi Arabia''s lead. This improved relations between Saudi Arabia and Iran also brought criticism from the United Arab Emirates, which criticised Saudi Arabia of abandoning UAE in its territorial disputes with Iran over three strategic Islands.

Saudi Arabia, Iran and the United States of America

As far as the relationship between Saudi Arabia and the U.S. is concerned, both countries have been strategic allies for more than sixty years. Saudi Arabia sees itself as a firm and generous partner of the U.S. in the cold war and in other international conflicts. The visits by US President George W. Bush to the Kingdom in 2008 reaffirmed these ties. Yet Saudis have always distanced themselves from American Foreign Policy, particularly with regards to Iran. Even when there was growing criticism against the former Iranian President, Mahmud Ahmadinejad, for his alleged hostile foreign policy in connection to Israel, Saudi Arabia recognised that Iran was a potential threat, and a regional power that was in position to create trouble within their borders. Therefore, Saudi Arabia''s security over time required accommodation and good relations with its geographic neighbors notably Iran. Iran with its population of 80 million, almost four times the population of Saudi Arabia, is separated from Saudi Arabia by only a few miles across the Gulf waters. It was here to stay, geographically speaking.

Prior to this visit, Saudi National Security advisor Prince Bandar bin Sultan, seen as one of the most pro-American figures in the region, had made a trip to Tehran to voice his government''s interest in building harmonious relations with Iran. During Iranian President Ahmadinejad''s 3 March 2007 visit, he discussed with King Abdullah the need to protect the Islamic world from enemy "conspiracies."

In 2007, President Ahmadinejad of Iran attended the first-ever annual summit of the Gulf Cooperation Council (GCC) which was established in 1988 that aimed to contain the ambitions of revolutionary Iran. This visit by the President of Iran was an event which signaled a possible change in relations. Yet soon after the meeting, Saudi Arabia, the most senior member of the six GCC member states invited Mr. Ahmadinejad to Saudi Arabia to take part in the annual Hajj (pilgrimage) to Mecca.

In 2009, Saudi Prince Faisal said in a press conference with Hillary Clinton that the "threat posed by Iran demanded a more immediate solution than sanctions." This statement was condemned by Iranian officials.

On 11 October 2011 US Attorney GeneralEric Holder accused Iran of planning to assassinate the Saudi-Arabian ambassador to the United States Adel Al-Jubbair.

In 2013, Saudi Ambassador to Britain Mohammed bin Nawaf bin Abdulaziz Al Saud wrote an editorial in The New York Times criticizing Saudi Arabia''s Western allies for not taking bold enough measures against Syria and Iran, thus destabilizing the Middle East and forcing Saudi Arabia to become more aggressive in international affairs. The Obama administration continues to reassure the Gulf states that regional security is a U.S. priority, but, as of December 2013, the Gulf states express skepticism.

Israel-Hamas conflict

Israel has constantly called Iran a staunch patron of Hamas, the current administration of the Gaza strip, whose militant wing has fought directly with Israel. Israeli leaders claim that Iran provides rhetoric support for Hamas, bitterly criticising Egypt and Saudi Arabia to break Israel''s economic blockade of Gaza. During his stint, Iranian President Ahmadinejad strongly condemned Israeli attacks on Gaza and put pressure on Arab and other Muslim countries to help Hamas. Iranian President, Ahmadinejad urged King Abdullah of Saudi Arabia to speak out against Israel''s attacks on Gaza. He also accused the Saudi King and other Arab leaders of being complicit in a "genocide" perpetrated against the Palestinians. Therefore, he demanded that all the Arab countries cut their, in-direct, ties with Israel. Iran has provided funding to Hamas and also supplied Hamas a number of Katyusha Grad Missiles.

Shia insurgency in the Yemen

Yemeni rebels, known as Houthis, who are a politically infused religious rebel group based in the Yemen, crossed into Saudi Arabia, whereby they killed two border guards and seized Saudi territory, including the strategically important Mount al-Doud.

This triggered the largest Saudi military operation since the Iraqi invasion of Kuwait in 1990. Yemen''s government, as well as the Arabs, accused Iran of arming the Houthis. Iran has heavily criticized Saudi Arabia for their intervention in the Shia insurgency in Yemen. Iran''s then president Ahmadinejad was quoted as saying: "Saudi Arabia was expected to mediate in Yemen''s internal conflict as an older brother and restore peace to the Muslim state, rather than launching military strike and pounding bombs on Muslim civilians in the north of Yemen," whilst Saudi foreign minister Saud Al Faisal counter-accused Iran of meddling in Yemen''s internal affairs. Ahmadinejad went even further saying: "Some Western states invaded the region (Afghanistan and Iraq) in the wake of the September 11 attacks, whilst Al-Qaeda''s main hub was located in another country in the region, which enjoys huge oil revenues and good relations with the United States and Western countries. There are some countries in the Middle East region that do not hold even a single election, don''t allow women to drive, but the US and European governments are supporting their undemocratic governments," in reference to Saudi Arabia.

Iranian general Mir-Faisal Baqerzadeh changed his name to Seyed Mohammad Baqerzadeh in opposition to what he viewed as Saudi crimes committed in Sa''adah.

Wikileaks

In November 2010, Wikileaks disclosed various confidential documents pertaining to the US and its allies which revealed that King Abdullah urged the US to attack Iran to destroy its nuclear weapons programme, describing Iran as a snake whose head should be cut off without any procrastination. The documents were dismissed by Iranian president Mahmoud Ahmadinejad, claiming them to be "organised to be released on a regular basis."

In 2012, in response to the global sanctions against Iran, Saudi Arabia offered to offset the loss of Iranian oil sales and Iran warned against this. The same year Turki Al Faisal, former head of Saudi General Intelligence and a Saudi royal, suggested that Saudi Arabia would support the U.S.-led sanctions against Iranian oil.